Coinbase coding interview
questions, leaked.
12 problems reported across recent Coinbase interviews. Top patterns: array, string, hash table. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Coinbase's interview is heavy on data structures and medium-difficulty problems that look deceptively simple until you hit edge cases. Out of 12 reported problems, nine are medium and only one is easy. Arrays dominate (8 problems), followed by strings (7) and hash tables (6). You're facing design questions that blur the line between implementation and optimization, and simulation problems that test whether you can code cleanly under pressure. If you blank on a design pattern mid-assessment, StealthCoder runs invisibly and surfaces a working solution in seconds.
Top problems at Coinbase
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Simple Bank System | MEDIUM | 100.0 | 61% | Array · Hash Table · Design |
| 02 | Zigzag Iterator | MEDIUM | 96.4 | 66% | Array · Design · Queue |
| 03 | Time Based Key-Value Store | MEDIUM | 90.4 | 49% | Hash Table · String · Binary Search |
| 04 | Decode the Message | EASY | 88.6 | 85% | Hash Table · String |
| 05 | Design In-Memory File System | HARD | 84.4 | 48% | Hash Table · String · Design |
| 06 | Design File System | MEDIUM | 67.5 | 64% | Hash Table · String · Design |
| 07 | Check if There is a Valid Partition For The Array | MEDIUM | 61.5 | 52% | Array · Dynamic Programming |
| 08 | Text Justification | HARD | 61.5 | 48% | Array · String · Simulation |
| 09 | Random Pick with Weight | MEDIUM | 61.5 | 48% | Array · Math · Binary Search |
| 10 | Number of Orders in the Backlog | MEDIUM | 53.1 | 52% | Array · Heap (Priority Queue) · Simulation |
| 11 | Evaluate Division | MEDIUM | 53.1 | 63% | Array · String · Depth-First Search |
| 12 | Find the Length of the Longest Common Prefix | MEDIUM | 53.1 | 56% | Array · Hash Table · String |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual Coinbase OA. The proctor cannot see it. Screen share cannot detect it. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoder- array8 · 67%
- string7 · 58%
- hash table6 · 50%
- design5 · 42%
- simulation3 · 25%
- trie3 · 25%
- binary search2 · 17%
- queue1 · 8%
- iterator1 · 8%
- sorting1 · 8%
The pattern here is clear: Coinbase doesn't care if you can solve a toy array problem. They want to see if you can design a system (Simple Bank System, Time Based Key-Value Store, In-Memory File System) and implement it without bugs. Arrays and strings appear together in 7 problems, often wrapped in design or simulation contexts. Hash tables anchor most of the harder questions. Binary search shows up twice but only in medium problems, so it's a secondary skill here. Trie appears in three problems, all tied to file-system or string-prefix challenges. The difficulty spike from medium to hard is sharp: expect String and Array to combine with Simulation in Text Justification, or design with Trie and Sorting in the file-system questions. If you've prepped on basic arrays but skipped design patterns, StealthCoder is your hedge for the live OA. One easy problem means the bulk of your prep should target the medium tier where most candidates stall.
Companies with similar patterns
If you prepped for Coinbase, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Coinbase.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Coinbase interview FAQ
How many array problems should I solve before the Coinbase interview?+
Eight out of 12 reported problems involve arrays. But don't grind 50 array problems. Focus on the ones that combine arrays with design or simulation: Simple Bank System, Zigzag Iterator, Text Justification, and Random Pick with Weight. These teach you how Coinbase actually tests arrays, not just raw sorting or searching.
Is hash table knowledge enough for Coinbase?+
Hash tables appear in 6 problems but almost never alone. They're mixed with design (Time Based Key-Value Store), strings (Decode the Message), or tries (Find the Length of the Longest Common Prefix). Study hash tables as a building block for system design, not as a standalone topic.
What should I prioritize: design or algorithms?+
Design is the primary filter. Five of the top problems are labeled 'Design', and many others (Simple Bank System, Zigzag Iterator) test system thinking. Spend 60% of prep time on design patterns and implementing clean APIs, 40% on algorithm optimization. Coinbase wants engineers who think about scalability and edge cases first.
How much should I worry about the two hard problems?+
The two hard problems (Design In-Memory File System, Text Justification) combine multiple topics: hash tables, strings, tries, sorting, and simulation. Don't memorize solutions. Instead, practice breaking down a complex problem into smaller components. If you hit a wall on the hard problem during the OA, focus on getting a working version out first.
Is one easy problem a good sign or a red flag?+
It's a red flag. One easy out of 12 means the interview is calibrated hard. That one easy problem (Decode the Message) is probably a warmup. Expect the assessment to jump straight into medium difficulty. You don't get a gentle ramp. Prepare accordingly by drilling medium problems first.